JP2008082505A - Rolling bearing for belt type continuously variable transmission and belt type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent surface staring point type separation caused by tangent force. <P>SOLUTION: Average roughness of a track surface of an outer ring 14 is set to 0.08 μm or more (a rolling surface of the outer ring 14 is roughened). Thus, since sliding of a rolling body 16 is restraining by making motion near to pure rolling, the tangent force between the outer ring 14 and the rolling body 16 is reduced, and the surface starting point type separation caused by the tangent force can be prevented, and the service life of a rolling bearing for a belt type continuously variable transmission can be improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rolling bearing for a belt type continuously variable transmission for supporting a rotating shaft of a belt type continuously variable transmission of an automobile.

Conventionally, as this type of technology, the outer ring is fitted and fixed to a part of the transmission case of the belt-type continuously variable transmission, and the inner ring is fitted and supported on the input-side rotating shaft or the output-side rotating shaft. There is a rolling bearing that rotatably supports a shaft inside a transmission case (see, for example, Patent Document 1).
In general, when the belt type continuously variable transmission is operated, CVT fluid is supplied to each movable part to lubricate each movable part and the rolling bearing. The CVT fluid uses a lubricating oil having a high traction coefficient (for example, 0.09 or more) in order to smoothly operate a torque converter, a gear mechanism, a hydraulic mechanism, a wet clutch, and the like to transmit power.
JP 2003-336703 A

However, in the above prior art, since a lubricating oil having a high traction coefficient is used, the rolling bearing used in the belt-type continuously variable transmission has a tangential force acting between the inner and outer rings and the rolling elements ( Traction) increases, and the surface-origin type peeling life may be shortened.
An object of the present invention is to provide a rolling bearing for a belt-type continuously variable transmission capable of improving the surface-origin type peeling life. .

  In order to solve the above problems, a rolling bearing for a belt-type continuously variable transmission according to the present invention includes an outer ring having a raceway surface on an inner peripheral surface, an inner ring having a raceway surface on an outer peripheral surface, and a raceway surface and an inner ring of the outer ring. A plurality of rolling elements that are rotatably disposed between the outer ring and the raceway surface, and the outer ring is fitted and supported in a fixed part, and the inner ring is rotated together with a pulley constituting a belt-type continuously variable transmission. And a belt-type continuously variable transmission rolling bearing that rotatably supports the pulley on the fixed portion, wherein an average roughness of the raceway surface of the outer ring is 0.08 μm or more. It is characterized by being 5 μm or less.

The average roughness of the rolling surface of the rolling element may be 0.03 μm or less.
On the other hand, the belt continuously variable transmission according to the present invention includes the belt bearing for the continuously variable transmission according to claim 1 or 2.
According to such a configuration, slip of the rolling element can be suppressed, and even if the traction coefficient of the CVT fluid is high (for example, 0.09 or more), there is no difference between the inner and outer rings and the rolling element. The tangential force can be reduced, and the surface-origin type peeling life can be improved.

Hereinafter, an embodiment in which the rolling bearing for a belt type continuously variable transmission according to the present invention is applied to a belt type continuously variable transmission will be described with reference to the drawings.
<Configuration of belt type continuously variable transmission>
As shown in FIG. 1, the belt type continuously variable transmission includes an input side mechanism 1, an output side mechanism 2, and an endless belt 3.
The input side mechanism 1 is rotatably supported by a pair of rolling bearings 4 and 4 at both ends, and is rotated by a driving source 5 such as an engine via a starting clutch 6 such as a torque converter. A driving pulley 8 provided at a portion located between the pair of rolling bearings 4 and 4 in the intermediate portion of the input rotating shaft 7 and a driving actuator 9 capable of expanding the groove width of the driving pulley 8. And comprising.

The output-side mechanism 2 includes an output-side rotating shaft 11 that is rotatably supported by a pair of rolling bearings 10 and 10 at both ends, and a pair of rolling bearings 10 and 10 at an intermediate portion between the output-side rotating shaft 11. A driven pulley 12 provided in a portion located therebetween, and a driven actuator 13 capable of expanding the groove width of the driven pulley 12 are configured.
The endless belt 3 is stretched between the driving pulley 8 and the driven pulley 12, and the power transmitted from the driving source 5 to the driving pulley 8 through the starting clutch 6 and the input rotating shaft 7 is driven by the driven pulley 12. (Output side rotating shaft 11).

As shown in FIG. 2, the rolling bearings 4 and 10 include an outer ring 14 having a raceway surface on the inner peripheral surface, an inner ring 15 having a raceway surface on the outer peripheral surface, a raceway surface of the outer ring 14, and a raceway surface of the inner ring 15. And a plurality of rolling elements 16 that are rotatably arranged between them.
The rolling bearings 4 and 10 have the outer ring 14 fitted and fixed to a part of the transmission case of the belt type continuously variable transmission, and the inner ring 15 is fitted and supported on the input side rotating shaft 7 or the output side rotating shaft 11. The rotary shafts 7 and 11 are rotatably supported inside the transmission case.

The average roughness Ra of the rolling surface of the outer ring 14 was 0.08 μm ≦ Ra ≦ 0.5 μm.
Furthermore, the average roughness Ra of the rolling surface of the rolling element 16 was Ra ≦ 0.03 μm.
Further, when the belt-type continuously variable transmission is operated, CVT fluid (lubricating oil having a traction coefficient of 0.09 or more) is supplied to each movable portion (input-side mechanism 1, output-side mechanism 2, endless belt 3). Each movable part and the rolling bearings 4 and 10 were lubricated.

<Operation and effect of rolling bearing>
As described above, in the rolling bearing for the belt type continuously variable transmission and the belt type continuously variable transmission according to the present embodiment, the average roughness of the raceway surface of the outer ring 14 is set to 0.08 μm or more, preferably 0.10 μm or more (the outer ring 14 The rolling surface of was roughened). For this reason, the movement is close to that of pure rolling, and the sliding of the rolling element 16 is suppressed. Therefore, even if the tangential force between the outer ring 14 and the rolling element 16 is reduced and the traction coefficient of the CVT fluid is high (0.09). Even in the above, it is possible to prevent the surface-origin type peeling due to the tangential force and to improve the life of the rolling bearing for the belt type continuously variable transmission.

  That is, generally, when the raceway surface of the outer ring 14 becomes rough, it tends to be considered that the tangential force between the outer ring 14 and the rolling element 16 becomes large and the surface-origin type peeling life is shortened. Therefore, even if the surface roughness of the outer ring 14 and the inner ring 15 on the driving side is increased at a high surface pressure position, the surface-origin type peeling life is not shortened.

  Further, since the raceway surface of the outer ring 14 is rough, in a non-load zone, the rolling surface of the rolling element 16 and the raceway surface of the outer ring 14 are pressed by pressing the rolling element 16 against the raceway surface of the outer ring 14 by centrifugal force. During this period, a force to rotate the rolling element 16 can be exerted to improve the rotation speed of the rolling element 16. Therefore, the difference in the rotation speed of the rolling element 16 between the load-loading zone and the non-loading zone can be reduced, the rolling slip of the rolling element 16 can be reduced, the tangential force can be reduced, and the surface-origin type peeling life can be improved.

  Incidentally, in the method of making the average roughness of the raceway surface of the outer ring 14 smaller than 0.08 (smooth the raceway surface), the rotational speeds of the input side rotary shaft 7 and the output side rotary shaft 11 (inner ring 15) are constant. If so, the rolling element 16 in the non-loading area is slower in rotation than the load-loading area, so that the rolling element 16 slips, and the tangential force between the outer ring 14 and the rolling element 16 increases. When the decrease in the rotation speed is large, the surface-origin type peeling life may be shortened.

  Further, even in the load zone, from the state in which the input side rotary shaft 7 and the output side rotary shaft 11 are stopped, the rotary shafts 7 and 11 start to rotate, and the rolling element 16 starts to rotate and revolve. When this is done, a force for rotating the rolling element 16 between the rolling surface of the rolling element 16 and the raceway surface of the outer ring 14 is exerted, so that the rotation speed of the rolling element 16 can be improved. Therefore, the time required for the peripheral speed of the rolling element 16 to reach a state close to the peripheral speed of the outer ring 14 and the inner ring 15 is shortened, the rotational slip of the rolling element 16 is reduced, and the tangential force is reduced. Surface-origin type peeling life can be improved.

  Incidentally, in the method of making the average roughness of the raceway surface of the outer ring 14 smaller than 0.08, when the input side rotating shaft 7 and the output side rotating shaft 11 start rotating when the vehicle is started from a stopped state. The rolling element 16 also starts rotating / revolving motion, and it takes a lot of time for the peripheral speed of the rolling element 16 to reach a state close to the peripheral speed of the outer ring 14 and the peripheral speed of the inner ring 15. Since a speed difference with the rolling element 16 is generated, the rolling element 16 slips, the tangential force between the outer ring 14 and the rolling element 16 increases, and the surface-origin type peeling life may be shortened.

Moreover, since the average roughness of the rolling surface of the outer ring 14 is 0.5 μm or less, heat generation due to the raceway surface of the outer ring 14 being too rough can be reduced, and seizure can be prevented.
Moreover, the average roughness of the rolling surface of the rolling element 16 was set to 0.03 μm or less, preferably 0.01 μm or less (the rolling element rolling surface was made smooth). Therefore, the tangential force between the outer ring 14 and the inner ring 15 and the rolling element 16 can be reduced, and surface-origin type separation can be prevented more reliably.

That is, in the load-bearing zone, when attention is paid to the contact between the outer ring 14 and the inner ring 15 and the rolling element 16, in the ball bearing and the self-aligning roller bearing, the rolling element 16 is in a region where the surface pressure is high at the center of the contact ellipse. The peripheral speed is higher than the peripheral speed of the outer ring 14 and the peripheral speed of the inner ring 15. That is, the rolling element 16 is on the driving side, and the outer ring 14 and the inner ring 15 are on the driven side.
Similarly, in a tapered roller bearing or a cylindrical roller bearing, theoretically, the sliding of the rolling element 16 is 0 and pure rolling is performed, but crowning for preventing separation of the edge load type is provided on the roller end face. In this case, the rolling element 16 is on the driving side and the outer ring 14 and the inner ring 15 are on the driven side at the center of the contact area.

  And since the surface-origin type peeling is likely to occur on the driven side, the surface roughness of the driving side has a significant effect on the surface-origin type peeling life, and the surface of the rolling element 16 on the driving side in the load-bearing area of the rolling bearing. The smaller the roughness, the longer the surface-origin type peel life. Note that the surface roughness of the outer ring 14 and the inner ring 15 on the driven side in the region where the surface pressure is high has little to do with the life of the surface-origin type peeling.

<Example>
Next, a plurality of belt type continuously variable transmission rolling bearings having different combinations of the average roughness of the raceway surface of the outer ring 14, the average roughness of the raceway surface of the inner ring 15, and the average roughness of the rolling surface of the rolling element 16 ( The test results of the test (life test) for measuring the surface-origin-type peeling life for each of the belt type continuously variable transmission rolling bearings of the above embodiment will be described with reference to the drawings.
In this life test, as a test object (Examples 1-21 in FIG. 3 and Comparative Examples 1-3), a deep groove ball in which the material of the outer ring 14, the inner ring 15, and the rolling element 16 is high carbon chrome bearing steel (SUJ2). A bearing 6206 that was tempered in an Rx gas atmosphere at 830 ° C. to 850 ° C. and then tempered at 180 ° C. to 240 ° C. was used.

Further, as the lubricating oil, CVT fluid NS2 mixed with 0.05 g of foreign matter having a hardness of HV870 and a size of 74 to 147 μm was used. Further, the test conditions were: test load: Fr = 6.4 kN, rotation speed: 0 (3 sec) ← → 3000 min ⁻¹ (30 sec).
Then, as shown in FIGS. 3 to 6, for each test object, the time until the surface-origin type delamination occurs with sample n = 12, and a Weibull plot of these times is created. From the results of the Weibull distribution, L10 The lifetime was calculated, and the calculated value was a ratio value (L10 life ratio) when the value of Comparative Example 1 (experimental result with the shortest lifetime) was “1”.
For the measurement of the surface roughness, a foam holy surf made by Taylor Hobson was used.

From FIG. 3 to FIG. 6, when the average roughness of the raceway surface of the outer ring 14 is in the range of 0 to 0.08 μm, the L10 life ratio improves as the average roughness increases (as the raceway surface of the outer ring 14 becomes rougher). It can be seen that the life ratio becomes saturated when the average roughness of the raceway surface becomes 0.08 μm or more.
Similarly, when the average roughness of the raceway surface of the inner ring 15 is in the range of 0 to 0.08 μm, the longer the average roughness (the coarser the raceway surface of the inner ring 15), the longer the L10 life ratio becomes. It can be seen that the life ratio is saturated when the average roughness of the surface is 0.08 μm or more.

Further, when the average roughness of the rolling surface of the rolling element 16 is larger than 0.03 μm, the L10 life ratio becomes longer as the average roughness becomes smaller (as the rolling surface of the rolling element 16 becomes smoother). It can be seen that the L10 life ratio is saturated when the average roughness of the rolling surface is 0.03 μm or less.
In this embodiment, an example in which the outer ring 14, the inner ring 15, and the rolling element 16 are formed of SUJ2 is shown, but the surface hardness of the raceway surface of the outer ring 14, the raceway surface of the inner ring 15, and the rolling surface of the rolling element 16 is shown. If HRC> 55, the same effect can be obtained with any material.

It is a block diagram which shows schematic structure of a belt type continuously variable transmission. It is a principal part enlarged view which expands and shows the rolling bearing of FIG. It is a list which shows the test result of a life test. It is explanatory drawing for demonstrating the relationship between outer ring | wheel roughness and a lifetime. It is explanatory drawing for demonstrating the relationship between inner ring roughness and a lifetime. It is explanatory drawing for demonstrating the relationship between rolling-element rolling surface roughness and a lifetime.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 is an input side mechanism, 2 is an output side mechanism, 3 is an endless belt, 4 and 10 are rolling bearings, 5 is a drive source, 6 is a starting clutch, 7 is an input side rotating shaft, 8 is a drive side pulley, 9 is drive Side actuator, 11 output side rotating shaft, 12 driven pulley, 13 driven actuator, 14 outer ring, 15 inner ring, 16 rolling element

Claims (3)

An outer ring having a raceway surface on the inner peripheral surface, an inner ring having a raceway surface on the outer peripheral surface, and a plurality of rolling elements rotatably arranged between the raceway surface of the outer ring and the raceway surface of the inner ring,
A belt type in which the outer ring is internally fitted and supported by a fixed part, the inner ring is externally fitted and supported by a part that rotates together with a pulley constituting a belt type continuously variable transmission, and the pulley is rotatably supported by the fixed part. A rolling bearing for a continuously variable transmission,
A rolling bearing for a belt-type continuously variable transmission, wherein an average roughness of a raceway surface of the outer ring is 0.08 μm or more and 0.5 μm or less.   The rolling bearing for a rolling belt type continuously variable transmission according to claim 1, wherein an average roughness of a rolling surface of the rolling element is 0.03 μm or less.   A belt type continuously variable transmission comprising the rolling bearing for a belt type continuously variable transmission according to claim 1 or 2.

Images